Add m-esr52 at 52.6.0

1 files changed, 2043 insertions, 0 deletions

diff --git a/widget/nsIWidget.h b/widget/nsIWidget.h
new file mode 100644
index 000000000..2d14cc107
--- /dev/null
+++ b/widget/nsIWidget.h
@@ -0,0 +1,2043 @@
+/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsIWidget_h__
+#define nsIWidget_h__
+
+#include "mozilla/UniquePtr.h"
+#include "nsISupports.h"
+#include "nsColor.h"
+#include "nsRect.h"
+#include "nsStringGlue.h"
+
+#include "nsCOMPtr.h"
+#include "nsWidgetInitData.h"
+#include "nsTArray.h"
+#include "nsITheme.h"
+#include "nsITimer.h"
+#include "nsRegionFwd.h"
+#include "nsXULAppAPI.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/layers/LayersTypes.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/widget/IMEData.h"
+#include "nsDataHashtable.h"
+#include "nsIObserver.h"
+#include "nsIWidgetListener.h"
+#include "FrameMetrics.h"
+#include "Units.h"
+
+// forward declarations
+class   nsIRollupListener;
+class   imgIContainer;
+class   nsIContent;
+class   ViewWrapper;
+class   nsIScreen;
+class   nsIRunnable;
+class   nsIKeyEventInPluginCallback;
+
+namespace mozilla {
+namespace dom {
+class TabChild;
+} // namespace dom
+namespace plugins {
+class PluginWidgetChild;
+} // namespace plugins
+namespace layers {
+class AsyncDragMetrics;
+class Composer2D;
+class Compositor;
+class CompositorBridgeChild;
+class LayerManager;
+class LayerManagerComposite;
+class PLayerTransactionChild;
+struct ScrollableLayerGuid;
+} // namespace layers
+namespace gfx {
+class DrawTarget;
+class SourceSurface;
+} // namespace gfx
+namespace widget {
+class TextEventDispatcher;
+class TextEventDispatcherListener;
+class CompositorWidget;
+class CompositorWidgetInitData;
+} // namespace widget
+} // namespace mozilla
+
+/**
+ * Callback function that processes events.
+ *
+ * The argument is actually a subtype (subclass) of WidgetEvent which carries
+ * platform specific information about the event. Platform specific code
+ * knows how to deal with it.
+ *
+ * The return value determines whether or not the default action should take
+ * place.
+ */
+typedef nsEventStatus (* EVENT_CALLBACK)(mozilla::WidgetGUIEvent* aEvent);
+
+// Hide the native window system's real window type so as to avoid
+// including native window system types and APIs. This is necessary
+// to ensure cross-platform code.
+typedef void* nsNativeWidget;
+
+/**
+ * Flags for the GetNativeData and SetNativeData functions
+ */
+#define NS_NATIVE_WINDOW      0
+#define NS_NATIVE_GRAPHIC     1
+#define NS_NATIVE_TMP_WINDOW  2
+#define NS_NATIVE_WIDGET      3
+#define NS_NATIVE_DISPLAY     4
+#define NS_NATIVE_REGION      5
+#define NS_NATIVE_OFFSETX     6
+#define NS_NATIVE_OFFSETY     7
+#define NS_NATIVE_PLUGIN_PORT 8
+#define NS_NATIVE_SCREEN      9
+// The toplevel GtkWidget containing this nsIWidget:
+#define NS_NATIVE_SHELLWIDGET 10
+// Has to match to NPNVnetscapeWindow, and shareable across processes
+// HWND on Windows and XID on X11
+#define NS_NATIVE_SHAREABLE_WINDOW 11
+#define NS_NATIVE_OPENGL_CONTEXT   12
+// See RegisterPluginWindowForRemoteUpdates
+#define NS_NATIVE_PLUGIN_ID        13
+// This is available only with GetNativeData() in parent process.  Anybody
+// shouldn't access this pointer as a valid pointer since the result may be
+// special value like NS_ONLY_ONE_NATIVE_IME_CONTEXT.  So, the result is just
+// an identifier of distinguishing a text composition is caused by which native
+// IME context.  Note that the result is only valid in the process.  So,
+// XP code should use nsIWidget::GetNativeIMEContext() instead of using this.
+#define NS_RAW_NATIVE_IME_CONTEXT  14
+#ifdef XP_MACOSX
+#define NS_NATIVE_PLUGIN_PORT_QD    100
+#define NS_NATIVE_PLUGIN_PORT_CG    101
+#endif
+#ifdef XP_WIN
+#define NS_NATIVE_TSF_THREAD_MGR       100
+#define NS_NATIVE_TSF_CATEGORY_MGR     101
+#define NS_NATIVE_TSF_DISPLAY_ATTR_MGR 102
+#define NS_NATIVE_ICOREWINDOW          103 // winrt specific
+#define NS_NATIVE_CHILD_WINDOW         104
+#define NS_NATIVE_CHILD_OF_SHAREABLE_WINDOW 105
+#endif
+#if defined(MOZ_WIDGET_GTK)
+// set/get nsPluginNativeWindowGtk, e10s specific
+#define NS_NATIVE_PLUGIN_OBJECT_PTR    104
+#ifdef MOZ_X11
+#define NS_NATIVE_COMPOSITOR_DISPLAY   105
+#endif // MOZ_X11
+#endif
+#ifdef MOZ_WIDGET_ANDROID
+#define NS_JAVA_SURFACE                100
+#define NS_PRESENTATION_WINDOW         101
+#define NS_PRESENTATION_SURFACE        102
+#endif
+
+#define NS_IWIDGET_IID \
+{ 0x06396bf6, 0x2dd8, 0x45e5, \
+  { 0xac, 0x45, 0x75, 0x26, 0x53, 0xb1, 0xc9, 0x80 } }
+
+/*
+ * Window shadow styles
+ * Also used for the -moz-window-shadow CSS property
+ */
+
+#define NS_STYLE_WINDOW_SHADOW_NONE             0
+#define NS_STYLE_WINDOW_SHADOW_DEFAULT          1
+#define NS_STYLE_WINDOW_SHADOW_MENU             2
+#define NS_STYLE_WINDOW_SHADOW_TOOLTIP          3
+#define NS_STYLE_WINDOW_SHADOW_SHEET            4
+
+/**
+ * Transparency modes
+ */
+
+enum nsTransparencyMode {
+  eTransparencyOpaque = 0,  // Fully opaque
+  eTransparencyTransparent, // Parts of the window may be transparent
+  eTransparencyGlass,       // Transparent parts of the window have Vista AeroGlass effect applied
+  eTransparencyBorderlessGlass // As above, but without a border around the opaque areas when there would otherwise be one with eTransparencyGlass
+};
+
+/**
+ * Cursor types.
+ */
+
+enum nsCursor {   ///(normal cursor,       usually rendered as an arrow)
+                eCursor_standard,
+                  ///(system is busy,      usually rendered as a hourglass or watch)
+                eCursor_wait,
+                  ///(Selecting something, usually rendered as an IBeam)
+                eCursor_select,
+                  ///(can hyper-link,      usually rendered as a human hand)
+                eCursor_hyperlink,
+                  ///(north/south/west/east edge sizing)
+                eCursor_n_resize,
+                eCursor_s_resize,
+                eCursor_w_resize,
+                eCursor_e_resize,
+                  ///(corner sizing)
+                eCursor_nw_resize,
+                eCursor_se_resize,
+                eCursor_ne_resize,
+                eCursor_sw_resize,
+                eCursor_crosshair,
+                eCursor_move,
+                eCursor_help,
+                eCursor_copy, // CSS3
+                eCursor_alias,
+                eCursor_context_menu,
+                eCursor_cell,
+                eCursor_grab,
+                eCursor_grabbing,
+                eCursor_spinning,
+                eCursor_zoom_in,
+                eCursor_zoom_out,
+                eCursor_not_allowed,
+                eCursor_col_resize,
+                eCursor_row_resize,
+                eCursor_no_drop,
+                eCursor_vertical_text,
+                eCursor_all_scroll,
+                eCursor_nesw_resize,
+                eCursor_nwse_resize,
+                eCursor_ns_resize,
+                eCursor_ew_resize,
+                eCursor_none,
+                // This one better be the last one in this list.
+                eCursorCount
+                };
+
+enum nsTopLevelWidgetZPlacement { // for PlaceBehind()
+  eZPlacementBottom = 0,  // bottom of the window stack
+  eZPlacementBelow,       // just below another widget
+  eZPlacementTop          // top of the window stack
+};
+
+/**
+ * Before the OS goes to sleep, this topic is notified.
+ */
+#define NS_WIDGET_SLEEP_OBSERVER_TOPIC "sleep_notification"
+
+/**
+ * After the OS wakes up, this topic is notified.
+ */
+#define NS_WIDGET_WAKE_OBSERVER_TOPIC "wake_notification"
+
+/**
+ * Before the OS suspends the current process, this topic is notified.  Some
+ * OS will kill processes that are suspended instead of resuming them.
+ * For that reason this topic may be useful to safely close down resources.
+ */
+#define NS_WIDGET_SUSPEND_PROCESS_OBSERVER_TOPIC "suspend_process_notification"
+
+/**
+ * After the current process resumes from being suspended, this topic is
+ * notified.
+ */
+#define NS_WIDGET_RESUME_PROCESS_OBSERVER_TOPIC "resume_process_notification"
+
+namespace mozilla {
+namespace widget {
+
+/**
+ * Size constraints for setting the minimum and maximum size of a widget.
+ * Values are in device pixels.
+ */
+struct SizeConstraints {
+  SizeConstraints()
+    : mMaxSize(NS_MAXSIZE, NS_MAXSIZE)
+  {
+  }
+
+  SizeConstraints(mozilla::LayoutDeviceIntSize aMinSize,
+                  mozilla::LayoutDeviceIntSize aMaxSize)
+  : mMinSize(aMinSize),
+    mMaxSize(aMaxSize)
+  {
+  }
+
+  mozilla::LayoutDeviceIntSize mMinSize;
+  mozilla::LayoutDeviceIntSize mMaxSize;
+};
+
+struct AutoObserverNotifier {
+  AutoObserverNotifier(nsIObserver* aObserver,
+                       const char* aTopic)
+    : mObserver(aObserver)
+    , mTopic(aTopic)
+  {
+  }
+
+  void SkipNotification()
+  {
+    mObserver = nullptr;
+  }
+
+  uint64_t SaveObserver()
+  {
+    if (!mObserver) {
+      return 0;
+    }
+    uint64_t observerId = ++sObserverId;
+    sSavedObservers.Put(observerId, mObserver);
+    SkipNotification();
+    return observerId;
+  }
+
+  ~AutoObserverNotifier()
+  {
+    if (mObserver) {
+      mObserver->Observe(nullptr, mTopic, nullptr);
+    }
+  }
+
+  static void NotifySavedObserver(const uint64_t& aObserverId,
+                                  const char* aTopic)
+  {
+    nsCOMPtr<nsIObserver> observer = sSavedObservers.Get(aObserverId);
+    if (!observer) {
+      MOZ_ASSERT(aObserverId == 0, "We should always find a saved observer for nonzero IDs");
+      return;
+    }
+
+    sSavedObservers.Remove(aObserverId);
+    observer->Observe(nullptr, aTopic, nullptr);
+  }
+
+private:
+  nsCOMPtr<nsIObserver> mObserver;
+  const char* mTopic;
+
+private:
+  static uint64_t sObserverId;
+  static nsDataHashtable<nsUint64HashKey, nsCOMPtr<nsIObserver>> sSavedObservers;
+};
+
+} // namespace widget
+} // namespace mozilla
+
+/**
+ * The base class for all the widgets. It provides the interface for
+ * all basic and necessary functionality.
+ */
+class nsIWidget : public nsISupports
+{
+  protected:
+    typedef mozilla::dom::TabChild TabChild;
+
+  public:
+    typedef mozilla::layers::Composer2D Composer2D;
+    typedef mozilla::layers::CompositorBridgeChild CompositorBridgeChild;
+    typedef mozilla::layers::AsyncDragMetrics AsyncDragMetrics;
+    typedef mozilla::layers::FrameMetrics FrameMetrics;
+    typedef mozilla::layers::LayerManager LayerManager;
+    typedef mozilla::layers::LayerManagerComposite LayerManagerComposite;
+    typedef mozilla::layers::LayersBackend LayersBackend;
+    typedef mozilla::layers::PLayerTransactionChild PLayerTransactionChild;
+    typedef mozilla::layers::ZoomConstraints ZoomConstraints;
+    typedef mozilla::widget::IMEMessage IMEMessage;
+    typedef mozilla::widget::IMENotification IMENotification;
+    typedef mozilla::widget::IMEState IMEState;
+    typedef mozilla::widget::InputContext InputContext;
+    typedef mozilla::widget::InputContextAction InputContextAction;
+    typedef mozilla::widget::NativeIMEContext NativeIMEContext;
+    typedef mozilla::widget::SizeConstraints SizeConstraints;
+    typedef mozilla::widget::TextEventDispatcher TextEventDispatcher;
+    typedef mozilla::widget::TextEventDispatcherListener
+      TextEventDispatcherListener;
+    typedef mozilla::LayoutDeviceIntMargin LayoutDeviceIntMargin;
+    typedef mozilla::LayoutDeviceIntPoint LayoutDeviceIntPoint;
+    typedef mozilla::LayoutDeviceIntRect LayoutDeviceIntRect;
+    typedef mozilla::LayoutDeviceIntRegion LayoutDeviceIntRegion;
+    typedef mozilla::LayoutDeviceIntSize LayoutDeviceIntSize;
+    typedef mozilla::ScreenIntPoint ScreenIntPoint;
+    typedef mozilla::DesktopIntRect DesktopIntRect;
+    typedef mozilla::CSSRect CSSRect;
+
+    // Used in UpdateThemeGeometries.
+    struct ThemeGeometry {
+      // The ThemeGeometryType value for the themed widget, see
+      // nsITheme::ThemeGeometryTypeForWidget.
+      nsITheme::ThemeGeometryType mType;
+      // The device-pixel rect within the window for the themed widget
+      LayoutDeviceIntRect mRect;
+
+      ThemeGeometry(nsITheme::ThemeGeometryType aType,
+                    const LayoutDeviceIntRect& aRect)
+        : mType(aType)
+        , mRect(aRect)
+      { }
+    };
+
+    NS_DECLARE_STATIC_IID_ACCESSOR(NS_IWIDGET_IID)
+
+    nsIWidget()
+      : mLastChild(nullptr)
+      , mPrevSibling(nullptr)
+      , mOnDestroyCalled(false)
+      , mWindowType(eWindowType_child)
+      , mZIndex(0)
+
+    {
+      ClearNativeTouchSequence(nullptr);
+    }
+
+
+    /**
+     * Create and initialize a widget.
+     *
+     * All the arguments can be null in which case a top level window
+     * with size 0 is created. The event callback function has to be
+     * provided only if the caller wants to deal with the events this
+     * widget receives.  The event callback is basically a preprocess
+     * hook called synchronously. The return value determines whether
+     * the event goes to the default window procedure or it is hidden
+     * to the os. The assumption is that if the event handler returns
+     * false the widget does not see the event. The widget should not
+     * automatically clear the window to the background color. The
+     * calling code must handle paint messages and clear the background
+     * itself.
+     *
+     * In practice at least one of aParent and aNativeParent will be null. If
+     * both are null the widget isn't parented (e.g. context menus or
+     * independent top level windows).
+     *
+     * The dimensions given in aRect are specified in the parent's
+     * device coordinate system.
+     * This must not be called for parentless widgets such as top-level
+     * windows, which use the desktop pixel coordinate system; a separate
+     * method is provided for these.
+     *
+     * @param     aParent       parent nsIWidget
+     * @param     aNativeParent native parent widget
+     * @param     aRect         the widget dimension
+     * @param     aInitData     data that is used for widget initialization
+     *
+     */
+    virtual MOZ_MUST_USE nsresult
+    Create(nsIWidget* aParent,
+           nsNativeWidget aNativeParent,
+           const LayoutDeviceIntRect& aRect,
+           nsWidgetInitData* aInitData = nullptr) = 0;
+
+    /*
+     * As above, but with aRect specified in DesktopPixel units (for top-level
+     * widgets).
+     * Default implementation just converts aRect to device pixels and calls
+     * through to device-pixel Create, but platforms may override this if the
+     * mapping is not straightforward or the native platform needs to use the
+     * desktop pixel values directly.
+     */
+    virtual MOZ_MUST_USE nsresult
+    Create(nsIWidget* aParent,
+           nsNativeWidget aNativeParent,
+           const DesktopIntRect& aRect,
+           nsWidgetInitData* aInitData = nullptr)
+    {
+        LayoutDeviceIntRect devPixRect =
+          RoundedToInt(aRect * GetDesktopToDeviceScale());
+        return Create(aParent, aNativeParent, devPixRect, aInitData);
+    }
+
+    /**
+     * Allocate, initialize, and return a widget that is a child of
+     * |this|.  The returned widget (if nonnull) has gone through the
+     * equivalent of CreateInstance(widgetCID) + Create(...).
+     *
+     * |CreateChild()| lets widget backends decide whether to parent
+     * the new child widget to this, nonnatively parent it, or both.
+     * This interface exists to support the PuppetWidget backend,
+     * which is entirely non-native.  All other params are the same as
+     * for |Create()|.
+     *
+     * |aForceUseIWidgetParent| forces |CreateChild()| to only use the
+     * |nsIWidget*| this, not its native widget (if it exists), when
+     * calling |Create()|.  This is a timid hack around poorly
+     * understood code, and shouldn't be used in new code.
+     */
+    virtual already_AddRefed<nsIWidget>
+    CreateChild(const LayoutDeviceIntRect& aRect,
+                nsWidgetInitData* aInitData = nullptr,
+                bool aForceUseIWidgetParent = false) = 0;
+
+    /**
+     * Attach to a top level widget.
+     *
+     * In cases where a top level chrome widget is being used as a content
+     * container, attach a secondary listener and update the device
+     * context. The primary widget listener will continue to be called for
+     * notifications relating to the top-level window, whereas other
+     * notifications such as painting and events will instead be called via
+     * the attached listener. SetAttachedWidgetListener should be used to
+     * assign the attached listener.
+     *
+     * aUseAttachedEvents if true, events are sent to the attached listener
+     * instead of the normal listener.
+     */
+    virtual void AttachViewToTopLevel(bool aUseAttachedEvents) = 0;
+
+    /**
+     * Accessor functions to get and set the attached listener. Used by
+     * nsView in connection with AttachViewToTopLevel above.
+     */
+    virtual void SetAttachedWidgetListener(nsIWidgetListener* aListener) = 0;
+    virtual nsIWidgetListener* GetAttachedWidgetListener() = 0;
+    virtual void SetPreviouslyAttachedWidgetListener(nsIWidgetListener* aListener) = 0;
+    virtual nsIWidgetListener* GetPreviouslyAttachedWidgetListener() = 0;
+
+    /**
+     * Accessor functions to get and set the listener which handles various
+     * actions for the widget.
+     */
+    //@{
+    virtual nsIWidgetListener* GetWidgetListener() = 0;
+    virtual void SetWidgetListener(nsIWidgetListener* alistener) = 0;
+    //@}
+
+    /**
+     * Close and destroy the internal native window.
+     * This method does not delete the widget.
+     */
+
+    virtual void Destroy() = 0;
+
+    /**
+     * Destroyed() returns true if Destroy() has been called already.
+     * Otherwise, false.
+     */
+    bool Destroyed() const { return mOnDestroyCalled; }
+
+
+    /**
+     * Reparent a widget
+     *
+     * Change the widget's parent. Null parents are allowed.
+     *
+     * @param     aNewParent   new parent
+     */
+    NS_IMETHOD SetParent(nsIWidget* aNewParent) = 0;
+
+    /**
+     * Return the parent Widget of this Widget or nullptr if this is a
+     * top level window
+     *
+     * @return the parent widget or nullptr if it does not have a parent
+     *
+     */
+    virtual nsIWidget* GetParent(void) = 0;
+
+    /**
+     * Return the top level Widget of this Widget
+     *
+     * @return the top level widget
+     */
+    virtual nsIWidget* GetTopLevelWidget() = 0;
+
+    /**
+     * Return the top (non-sheet) parent of this Widget if it's a sheet,
+     * or nullptr if this isn't a sheet (or some other error occurred).
+     * Sheets are only supported on some platforms (currently only OS X).
+     *
+     * @return the top (non-sheet) parent widget or nullptr
+     *
+     */
+    virtual nsIWidget* GetSheetWindowParent(void) = 0;
+
+    /**
+     * Return the physical DPI of the screen containing the window ...
+     * the number of device pixels per inch.
+     */
+    virtual float GetDPI() = 0;
+
+    /**
+     * Return the scaling factor between device pixels and the platform-
+     * dependent "desktop pixels" used to manage window positions on a
+     * potentially multi-screen, mixed-resolution desktop.
+     */
+    virtual mozilla::DesktopToLayoutDeviceScale GetDesktopToDeviceScale() = 0;
+
+    /**
+     * Return the default scale factor for the window. This is the
+     * default number of device pixels per CSS pixel to use. This should
+     * depend on OS/platform settings such as the Mac's "UI scale factor"
+     * or Windows' "font DPI". This will take into account Gecko preferences
+     * overriding the system setting.
+     */
+    mozilla::CSSToLayoutDeviceScale GetDefaultScale();
+
+    /**
+     * Return the Gecko override of the system default scale, if any;
+     * returns <= 0.0 if the system scale should be used as-is.
+     * nsIWidget::GetDefaultScale() [above] takes this into account.
+     * It is exposed here so that code that wants to check for a
+     * default-scale override without having a widget on hand can
+     * easily access the same value.
+     * Note that any scale override is a browser-wide value, whereas
+     * the default GetDefaultScale value (when no override is present)
+     * may vary between widgets (or screens).
+     */
+    static double DefaultScaleOverride();
+
+    /**
+     * Return the first child of this widget.  Will return null if
+     * there are no children.
+     */
+    nsIWidget* GetFirstChild() const {
+        return mFirstChild;
+    }
+
+    /**
+     * Return the last child of this widget.  Will return null if
+     * there are no children.
+     */
+    nsIWidget* GetLastChild() const {
+        return mLastChild;
+    }
+
+    /**
+     * Return the next sibling of this widget
+     */
+    nsIWidget* GetNextSibling() const {
+        return mNextSibling;
+    }
+
+    /**
+     * Set the next sibling of this widget
+     */
+    void SetNextSibling(nsIWidget* aSibling) {
+        mNextSibling = aSibling;
+    }
+
+    /**
+     * Return the previous sibling of this widget
+     */
+    nsIWidget* GetPrevSibling() const {
+        return mPrevSibling;
+    }
+
+    /**
+     * Set the previous sibling of this widget
+     */
+    void SetPrevSibling(nsIWidget* aSibling) {
+        mPrevSibling = aSibling;
+    }
+
+    /**
+     * Show or hide this widget
+     *
+     * @param aState true to show the Widget, false to hide it
+     *
+     */
+    NS_IMETHOD Show(bool aState) = 0;
+
+    /**
+     * Make the window modal.
+     */
+    virtual void SetModal(bool aModal) = 0;
+
+    /**
+     * Make the non-modal window opened by modal window fake-modal, that will
+     * call SetFakeModal(false) on destroy on Cocoa.
+     */
+    virtual void SetFakeModal(bool aModal)
+    {
+        SetModal(aModal);
+    }
+
+    /**
+     * Are we app modal. Currently only implemented on Cocoa.
+     */
+    virtual bool IsRunningAppModal()
+    {
+      return false;
+    }
+
+    /**
+     * The maximum number of simultaneous touch contacts supported by the device.
+     * In the case of devices with multiple digitizers (e.g. multiple touch screens),
+     * the value will be the maximum of the set of maximum supported contacts by
+     * each individual digitizer.
+     */
+    virtual uint32_t GetMaxTouchPoints() const = 0;
+
+    /**
+     * Returns whether the window is visible
+     *
+     */
+    virtual bool IsVisible() const = 0;
+
+    /**
+     * Perform platform-dependent sanity check on a potential window position.
+     * This is guaranteed to work only for top-level windows.
+     *
+     * @param aAllowSlop: if true, allow the window to slop offscreen;
+     *                    the window should be partially visible. if false,
+     *                    force the entire window onscreen (or at least
+     *                    the upper-left corner, if it's too large).
+     * @param aX in: an x position expressed in screen coordinates.
+     *           out: the x position constrained to fit on the screen(s).
+     * @param aY in: an y position expressed in screen coordinates.
+     *           out: the y position constrained to fit on the screen(s).
+     *
+     **/
+    virtual void ConstrainPosition(bool aAllowSlop,
+                                   int32_t *aX,
+                                   int32_t *aY) = 0;
+
+    /**
+     * NOTE:
+     *
+     * For a top-level window widget, the "parent's coordinate system" is the
+     * "global" display pixel coordinate space, *not* device pixels (which
+     * may be inconsistent between multiple screens, at least in the Mac OS
+     * case with mixed hi-dpi and lo-dpi displays). This applies to all the
+     * following Move and Resize widget APIs.
+     *
+     * The display-/device-pixel distinction becomes important for (at least)
+     * Mac OS X with Hi-DPI (retina) displays, and Windows when the UI scale
+     * factor is set to other than 100%.
+     *
+     * The Move and Resize methods take floating-point parameters, rather than
+     * integer ones. This is important when manipulating top-level widgets,
+     * where the coordinate system may not be an integral multiple of the
+     * device-pixel space.
+     **/
+
+    /**
+     * Move this widget.
+     *
+     * Coordinates refer to the top-left of the widget.  For toplevel windows
+     * with decorations, this is the top-left of the titlebar and frame .
+     *
+     * @param aX the new x position expressed in the parent's coordinate system
+     * @param aY the new y position expressed in the parent's coordinate system
+     *
+     **/
+    NS_IMETHOD Move(double aX, double aY) = 0;
+
+    /**
+     * Reposition this widget so that the client area has the given offset.
+     *
+     * @param aX       the new x offset of the client area expressed as an
+     *                 offset from the origin of the client area of the parent
+     *                 widget (for root widgets and popup widgets it is in
+     *                 screen coordinates)
+     * @param aY       the new y offset of the client area expressed as an
+     *                 offset from the origin of the client area of the parent
+     *                 widget (for root widgets and popup widgets it is in
+     *                 screen coordinates)
+     *
+     **/
+    NS_IMETHOD MoveClient(double aX, double aY) = 0;
+
+    /**
+     * Resize this widget. Any size constraints set for the window by a
+     * previous call to SetSizeConstraints will be applied.
+     *
+     * @param aWidth  the new width expressed in the parent's coordinate system
+     * @param aHeight the new height expressed in the parent's coordinate system
+     * @param aRepaint whether the widget should be repainted
+     *
+     */
+    NS_IMETHOD Resize(double aWidth,
+                      double aHeight,
+                      bool   aRepaint) = 0;
+
+    /**
+     * Move or resize this widget. Any size constraints set for the window by
+     * a previous call to SetSizeConstraints will be applied.
+     *
+     * @param aX       the new x position expressed in the parent's coordinate system
+     * @param aY       the new y position expressed in the parent's coordinate system
+     * @param aWidth   the new width expressed in the parent's coordinate system
+     * @param aHeight  the new height expressed in the parent's coordinate system
+     * @param aRepaint whether the widget should be repainted if the size changes
+     *
+     */
+    NS_IMETHOD Resize(double aX,
+                      double aY,
+                      double aWidth,
+                      double aHeight,
+                      bool   aRepaint) = 0;
+
+    /**
+     * Resize the widget so that the inner client area has the given size.
+     *
+     * @param aWidth   the new width of the client area.
+     * @param aHeight  the new height of the client area.
+     * @param aRepaint whether the widget should be repainted
+     *
+     */
+    NS_IMETHOD ResizeClient(double aWidth,
+                            double aHeight,
+                            bool   aRepaint) = 0;
+
+    /**
+     * Resize and reposition the widget so tht inner client area has the given
+     * offset and size.
+     *
+     * @param aX       the new x offset of the client area expressed as an
+     *                 offset from the origin of the client area of the parent
+     *                 widget (for root widgets and popup widgets it is in
+     *                 screen coordinates)
+     * @param aY       the new y offset of the client area expressed as an
+     *                 offset from the origin of the client area of the parent
+     *                 widget (for root widgets and popup widgets it is in
+     *                 screen coordinates)
+     * @param aWidth   the new width of the client area.
+     * @param aHeight  the new height of the client area.
+     * @param aRepaint whether the widget should be repainted
+     *
+     */
+    NS_IMETHOD ResizeClient(double aX,
+                            double aY,
+                            double aWidth,
+                            double aHeight,
+                            bool   aRepaint) = 0;
+
+    /**
+     * Sets the widget's z-index.
+     */
+    virtual void SetZIndex(int32_t aZIndex) = 0;
+
+    /**
+     * Gets the widget's z-index.
+     */
+    int32_t GetZIndex()
+    {
+      return mZIndex;
+    }
+
+    /**
+     * Position this widget just behind the given widget. (Used to
+     * control z-order for top-level widgets. Get/SetZIndex by contrast
+     * control z-order for child widgets of other widgets.)
+     * @param aPlacement top, bottom, or below a widget
+     *                   (if top or bottom, param aWidget is ignored)
+     * @param aWidget    widget to place this widget behind
+     *                   (only if aPlacement is eZPlacementBelow).
+     *                   null is equivalent to aPlacement of eZPlacementTop
+     * @param aActivate  true to activate the widget after placing it
+     */
+    virtual void PlaceBehind(nsTopLevelWidgetZPlacement aPlacement,
+                             nsIWidget *aWidget, bool aActivate) = 0;
+
+    /**
+     * Minimize, maximize or normalize the window size.
+     * Takes a value from nsSizeMode (see nsIWidgetListener.h)
+     */
+    virtual void SetSizeMode(nsSizeMode aMode) = 0;
+
+    /**
+     * Return size mode (minimized, maximized, normalized).
+     * Returns a value from nsSizeMode (see nsIWidgetListener.h)
+     */
+    virtual nsSizeMode SizeMode() = 0;
+
+    /**
+     * Enable or disable this Widget
+     *
+     * @param aState true to enable the Widget, false to disable it.
+     *
+     */
+    NS_IMETHOD Enable(bool aState) = 0;
+
+    /**
+     * Ask whether the widget is enabled
+     */
+    virtual bool IsEnabled() const = 0;
+
+    /**
+     * Request activation of this window or give focus to this widget.
+     *
+     * @param aRaise If true, this function requests activation of this
+     *               widget's toplevel window.
+     *               If false, the appropriate toplevel window (which in
+     *               the case of popups may not be this widget's toplevel
+     *               window) is already active.
+     */
+    NS_IMETHOD SetFocus(bool aRaise = false) = 0;
+
+    /**
+     * Get this widget's outside dimensions relative to its parent widget. For
+     * popup widgets the returned rect is in screen coordinates and not
+     * relative to its parent widget.
+     *
+     * @return the x, y, width and height of this widget.
+     */
+    virtual LayoutDeviceIntRect GetBounds() = 0;
+
+    /**
+     * Get this widget's outside dimensions in device coordinates. This
+     * includes any title bar on the window.
+     *
+     * @return the x, y, width and height of this widget.
+     */
+    virtual LayoutDeviceIntRect GetScreenBounds() = 0;
+
+    /**
+     * Similar to GetScreenBounds except that this function will always
+     * get the size when the widget is in the nsSizeMode_Normal size mode
+     * even if the current size mode is not nsSizeMode_Normal.
+     * This method will fail if the size mode is not nsSizeMode_Normal and
+     * the platform doesn't have the ability.
+     * This method will always succeed if the current size mode is
+     * nsSizeMode_Normal.
+     *
+     * @param aRect   On return it holds the  x, y, width and height of
+     *                this widget.
+     */
+    virtual MOZ_MUST_USE nsresult
+    GetRestoredBounds(LayoutDeviceIntRect& aRect) = 0;
+
+    /**
+     * Get this widget's client area bounds, if the window has a 3D border
+     * appearance this returns the area inside the border. The position is the
+     * position of the client area relative to the client area of the parent
+     * widget (for root widgets and popup widgets it is in screen coordinates).
+     *
+     * @return the x, y, width and height of the client area of this widget.
+     */
+    virtual LayoutDeviceIntRect GetClientBounds() = 0;
+
+    /**
+     * Sets the non-client area dimensions of the window. Pass -1 to restore
+     * the system default frame size for that border. Pass zero to remove
+     * a border, or pass a specific value adjust a border. Units are in
+     * pixels. (DPI dependent)
+     *
+     * Platform notes:
+     *  Windows: shrinking top non-client height will remove application
+     *  icon and window title text. Glass desktops will refuse to set
+     *  dimensions between zero and size < system default.
+     *
+     */
+    NS_IMETHOD SetNonClientMargins(LayoutDeviceIntMargin& aMargins) = 0;
+
+    /**
+     * Get the client offset from the window origin.
+     *
+     * @return the x and y of the offset.
+     */
+    virtual LayoutDeviceIntPoint GetClientOffset() = 0;
+
+    /**
+     * Equivalent to GetClientBounds but only returns the size.
+     */
+    virtual LayoutDeviceIntSize GetClientSize() {
+      // Depending on the backend, overloading this method may be useful if
+      // requesting the client offset is expensive.
+      return GetClientBounds().Size();
+    }
+
+    /**
+     * Set the background color for this widget
+     *
+     * @param aColor the new background color
+     *
+     */
+
+    virtual void SetBackgroundColor(const nscolor &aColor) { }
+
+    /**
+     * Get the cursor for this widget.
+     *
+     * @return this widget's cursor.
+     */
+
+    virtual nsCursor GetCursor(void) = 0;
+
+    /**
+     * Set the cursor for this widget
+     *
+     * @param aCursor the new cursor for this widget
+     */
+
+    NS_IMETHOD SetCursor(nsCursor aCursor) = 0;
+
+    /**
+     * If a cursor type is currently cached locally for this widget, clear the
+     * cached cursor to force an update on the next SetCursor call.
+     */
+
+    virtual void ClearCachedCursor() = 0;
+
+    /**
+     * Sets an image as the cursor for this widget.
+     *
+     * @param aCursor the cursor to set
+     * @param aX the X coordinate of the hotspot (from left).
+     * @param aY the Y coordinate of the hotspot (from top).
+     * @retval NS_ERROR_NOT_IMPLEMENTED if setting images as cursors is not
+     *         supported
+     */
+    NS_IMETHOD SetCursor(imgIContainer* aCursor,
+                         uint32_t aHotspotX, uint32_t aHotspotY) = 0;
+
+    /**
+     * Get the window type of this widget.
+     */
+    nsWindowType WindowType() { return mWindowType; }
+
+    /**
+     * Determines if this widget is one of the three types of plugin widgets.
+     */
+    bool IsPlugin() {
+      return mWindowType == eWindowType_plugin ||
+             mWindowType == eWindowType_plugin_ipc_chrome ||
+             mWindowType == eWindowType_plugin_ipc_content;
+    }
+
+    /**
+     * Set the transparency mode of the top-level window containing this widget.
+     * So, e.g., if you call this on the widget for an IFRAME, the top level
+     * browser window containing the IFRAME actually gets set. Be careful.
+     *
+     * This can fail if the platform doesn't support
+     * transparency/glass. By default widgets are not
+     * transparent.  This will also fail if the toplevel window is not
+     * a Mozilla window, e.g., if the widget is in an embedded
+     * context.
+     *
+     * After transparency/glass has been enabled, the initial alpha channel
+     * value for all pixels is 1, i.e., opaque.
+     * If the window is resized then the alpha channel values for
+     * all pixels are reset to 1.
+     * Pixel RGB color values are already premultiplied with alpha channel values.
+     */
+    virtual void SetTransparencyMode(nsTransparencyMode aMode) = 0;
+
+    /**
+     * Get the transparency mode of the top-level window that contains this
+     * widget.
+     */
+    virtual nsTransparencyMode GetTransparencyMode() = 0;
+
+    /**
+     * This represents a command to set the bounds and clip region of
+     * a child widget.
+     */
+    struct Configuration {
+        nsCOMPtr<nsIWidget> mChild;
+        uintptr_t mWindowID; // e10s specific, the unique plugin port id
+        bool mVisible; // e10s specific, widget visibility
+        LayoutDeviceIntRect mBounds;
+        nsTArray<LayoutDeviceIntRect> mClipRegion;
+    };
+
+    /**
+     * Sets the clip region of each mChild (which must actually be a child
+     * of this widget) to the union of the pixel rects given in
+     * mClipRegion, all relative to the top-left of the child
+     * widget. Clip regions are not implemented on all platforms and only
+     * need to actually work for children that are plugins.
+     *
+     * Also sets the bounds of each child to mBounds.
+     *
+     * This will invalidate areas of the children that have changed, but
+     * does not need to invalidate any part of this widget.
+     *
+     * Children should be moved in the order given; the array is
+     * sorted so to minimize unnecessary invalidation if children are
+     * moved in that order.
+     */
+    virtual nsresult ConfigureChildren(const nsTArray<Configuration>& aConfigurations) = 0;
+    virtual nsresult SetWindowClipRegion(const nsTArray<LayoutDeviceIntRect>& aRects,
+                                         bool aIntersectWithExisting) = 0;
+
+    /**
+     * Appends to aRects the rectangles constituting this widget's clip
+     * region. If this widget is not clipped, appends a single rectangle
+     * (0, 0, bounds.width, bounds.height).
+     */
+    virtual void GetWindowClipRegion(nsTArray<LayoutDeviceIntRect>* aRects) = 0;
+
+    /**
+     * Register or unregister native plugin widgets which receive Configuration
+     * data from the content process via the compositor.
+     *
+     * Lookups are used by the main thread via the compositor to lookup widgets
+     * based on a unique window id. On Windows and Linux this is the
+     * NS_NATIVE_PLUGIN_PORT (hwnd/XID). This tracking maintains a reference to
+     * widgets held. Consumers are responsible for removing widgets from this
+     * list.
+     */
+    virtual void RegisterPluginWindowForRemoteUpdates() = 0;
+    virtual void UnregisterPluginWindowForRemoteUpdates() = 0;
+    static nsIWidget* LookupRegisteredPluginWindow(uintptr_t aWindowID);
+
+    /**
+     * Iterates across the list of registered plugin widgets and updates thier
+     * visibility based on which plugins are included in the 'visible' list.
+     *
+     * The compositor knows little about tabs, but it does know which plugin
+     * widgets are currently included in the visible layer tree. It calls this
+     * helper to hide widgets it knows nothing about.
+     */
+    static void UpdateRegisteredPluginWindowVisibility(uintptr_t aOwnerWidget,
+                                                       nsTArray<uintptr_t>& aPluginIds);
+
+#if defined(XP_WIN)
+    /**
+     * Iterates over the list of registered plugins and for any that are owned
+     * by aOwnerWidget and visible it takes a snapshot.
+     *
+     * @param aOwnerWidget only captures visible widgets owned by this
+     */
+    static void CaptureRegisteredPlugins(uintptr_t aOwnerWidget);
+
+    /**
+     * Take a scroll capture for this widget if possible.
+     */
+    virtual void UpdateScrollCapture() = 0;
+
+    /**
+     * Creates an async ImageContainer to hold scroll capture images that can be
+     * used if the plugin is hidden during scroll.
+     * @return the async container ID of the created ImageContainer.
+     */
+    virtual uint64_t CreateScrollCaptureContainer() = 0;
+#endif
+
+    /**
+     * Set the shadow style of the window.
+     *
+     * Ignored on child widgets and on non-Mac platforms.
+     */
+    virtual void SetWindowShadowStyle(int32_t aStyle) = 0;
+
+    /*
+     * On Mac OS X, this method shows or hides the pill button in the titlebar
+     * that's used to collapse the toolbar.
+     *
+     * Ignored on child widgets and on non-Mac platforms.
+     */
+    virtual void SetShowsToolbarButton(bool aShow) = 0;
+
+    /*
+     * On Mac OS X Lion, this method shows or hides the full screen button in
+     * the titlebar that handles native full screen mode.
+     *
+     * Ignored on child widgets, non-Mac platforms, & pre-Lion Mac.
+     */
+    virtual void SetShowsFullScreenButton(bool aShow) = 0;
+
+    enum WindowAnimationType {
+      eGenericWindowAnimation,
+      eDocumentWindowAnimation
+    };
+
+    /**
+     * Sets the kind of top-level window animation this widget should have.  On
+     * Mac OS X, this causes a particular kind of animation to be shown when the
+     * window is first made visible.
+     *
+     * Ignored on child widgets and on non-Mac platforms.
+     */
+    virtual void SetWindowAnimationType(WindowAnimationType aType) = 0;
+
+    /**
+     * Specifies whether the window title should be drawn even if the window
+     * contents extend into the titlebar. Ignored on windows that don't draw
+     * in the titlebar. Only implemented on OS X.
+     */
+    virtual void SetDrawsTitle(bool aDrawTitle) {}
+
+    /**
+     * Indicates whether the widget should attempt to make titlebar controls
+     * easier to see on dark titlebar backgrounds.
+     */
+    virtual void SetUseBrightTitlebarForeground(bool aBrightForeground) {}
+
+    /**
+     * Hide window chrome (borders, buttons) for this widget.
+     *
+     */
+    NS_IMETHOD HideWindowChrome(bool aShouldHide) = 0;
+
+    enum FullscreenTransitionStage
+    {
+      eBeforeFullscreenToggle,
+      eAfterFullscreenToggle
+    };
+
+    /**
+     * Prepares for fullscreen transition and returns whether the widget
+     * supports fullscreen transition. If this method returns false,
+     * PerformFullscreenTransition() must never be called. Otherwise,
+     * caller should call that method twice with "before" and "after"
+     * stages respectively in order. In the latter case, this method may
+     * return some data via aData pointer. Caller must pass that data to
+     * PerformFullscreenTransition() if any, and caller is responsible
+     * for releasing that data.
+     */
+    virtual bool PrepareForFullscreenTransition(nsISupports** aData) = 0;
+
+    /**
+     * Performs fullscreen transition. This method returns immediately,
+     * and will post aCallback to the main thread when the transition
+     * finishes.
+     */
+    virtual void PerformFullscreenTransition(FullscreenTransitionStage aStage,
+                                             uint16_t aDuration,
+                                             nsISupports* aData,
+                                             nsIRunnable* aCallback) = 0;
+
+    /**
+     * Return the screen the widget is in, or null if we don't know.
+     */
+    virtual already_AddRefed<nsIScreen> GetWidgetScreen() = 0;
+
+    /**
+     * Put the toplevel window into or out of fullscreen mode.
+     * If aTargetScreen is given, attempt to go fullscreen on that screen,
+     * if possible.  (If not, it behaves as if aTargetScreen is null.)
+     * If !aFullScreen, aTargetScreen is ignored.
+     * aTargetScreen support is currently only implemented on Windows.
+     *
+     * @return NS_OK if the widget is setup properly for fullscreen and
+     * FullscreenChanged callback has been or will be called. If other
+     * value is returned, the caller should continue the change itself.
+     */
+    virtual nsresult MakeFullScreen(bool aFullScreen,
+                                    nsIScreen* aTargetScreen = nullptr) = 0;
+
+    /**
+     * Same as MakeFullScreen, except that, on systems which natively
+     * support fullscreen transition, calling this method explicitly
+     * requests that behavior.
+     * It is currently only supported on OS X 10.7+.
+     */
+    virtual nsresult MakeFullScreenWithNativeTransition(
+      bool aFullScreen, nsIScreen* aTargetScreen = nullptr)
+    {
+      return MakeFullScreen(aFullScreen, aTargetScreen);
+    }
+
+    /**
+     * Invalidate a specified rect for a widget so that it will be repainted
+     * later.
+     */
+    NS_IMETHOD Invalidate(const LayoutDeviceIntRect& aRect) = 0;
+
+    enum LayerManagerPersistence
+    {
+      LAYER_MANAGER_CURRENT = 0,
+      LAYER_MANAGER_PERSISTENT
+    };
+
+    /**
+     * Return the widget's LayerManager. The layer tree for that
+     * LayerManager is what gets rendered to the widget.
+     */
+    inline LayerManager* GetLayerManager()
+    {
+        return GetLayerManager(nullptr, mozilla::layers::LayersBackend::LAYERS_NONE,
+                               LAYER_MANAGER_CURRENT);
+    }
+
+    inline LayerManager* GetLayerManager(LayerManagerPersistence aPersistence)
+    {
+        return GetLayerManager(nullptr, mozilla::layers::LayersBackend::LAYERS_NONE,
+                               aPersistence);
+    }
+
+    /**
+     * Like GetLayerManager(), but prefers creating a layer manager of
+     * type |aBackendHint| instead of what would normally be created.
+     * LayersBackend::LAYERS_NONE means "no hint".
+     */
+    virtual LayerManager* GetLayerManager(PLayerTransactionChild* aShadowManager,
+                                          LayersBackend aBackendHint,
+                                          LayerManagerPersistence aPersistence = LAYER_MANAGER_CURRENT) = 0;
+
+    /**
+     * Called before each layer manager transaction to allow any preparation
+     * for DrawWindowUnderlay/Overlay that needs to be on the main thread.
+     *
+     * Always called on the main thread.
+     */
+    virtual void PrepareWindowEffects() = 0;
+
+    /**
+     * Called when Gecko knows which themed widgets exist in this window.
+     * The passed array contains an entry for every themed widget of the right
+     * type (currently only NS_THEME_TOOLBAR) within the window, except for
+     * themed widgets which are transformed or have effects applied to them
+     * (e.g. CSS opacity or filters).
+     * This could sometimes be called during display list construction
+     * outside of painting.
+     * If called during painting, it will be called before we actually
+     * paint anything.
+     */
+    virtual void UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries) = 0;
+
+    /**
+     * Informs the widget about the region of the window that is opaque.
+     *
+     * @param aOpaqueRegion the region of the window that is opaque.
+     */
+    virtual void UpdateOpaqueRegion(const LayoutDeviceIntRegion& aOpaqueRegion) {}
+
+    /**
+     * Informs the widget about the region of the window that is draggable.
+     */
+    virtual void UpdateWindowDraggingRegion(const LayoutDeviceIntRegion& aRegion) {}
+
+    /**
+     * Tells the widget whether the given input block results in a swipe.
+     * Should be called in response to a WidgetWheelEvent that has
+     * mFlags.mCanTriggerSwipe set on it.
+     */
+    virtual void ReportSwipeStarted(uint64_t aInputBlockId, bool aStartSwipe) {}
+
+    /**
+     * Internal methods
+     */
+
+    //@{
+    virtual void AddChild(nsIWidget* aChild) = 0;
+    virtual void RemoveChild(nsIWidget* aChild) = 0;
+    virtual void* GetNativeData(uint32_t aDataType) = 0;
+    virtual void SetNativeData(uint32_t aDataType, uintptr_t aVal) = 0;
+    virtual void FreeNativeData(void * data, uint32_t aDataType) = 0;//~~~
+
+    //@}
+
+    /**
+     * Set the widget's title.
+     * Must be called after Create.
+     *
+     * @param aTitle string displayed as the title of the widget
+     */
+
+    NS_IMETHOD SetTitle(const nsAString& aTitle) = 0;
+
+    /**
+     * Set the widget's icon.
+     * Must be called after Create.
+     *
+     * @param anIconSpec string specifying the icon to use; convention is to pass
+     *                   a resource: URL from which a platform-dependent resource
+     *                   file name will be constructed
+     */
+
+    NS_IMETHOD SetIcon(const nsAString& anIconSpec) = 0;
+
+    /**
+     * Return this widget's origin in screen coordinates.
+     *
+     * @return screen coordinates stored in the x,y members
+     */
+    virtual LayoutDeviceIntPoint WidgetToScreenOffset() = 0;
+
+    /**
+     * Given the specified client size, return the corresponding window size,
+     * which includes the area for the borders and titlebar. This method
+     * should work even when the window is not yet visible.
+     */
+    virtual LayoutDeviceIntSize ClientToWindowSize(
+                const LayoutDeviceIntSize& aClientSize) = 0;
+
+    /**
+     * Dispatches an event to the widget
+     *
+     */
+    NS_IMETHOD DispatchEvent(mozilla::WidgetGUIEvent* event,
+                             nsEventStatus & aStatus) = 0;
+
+    /**
+     * Dispatches an event to APZ only.
+     * No-op in the child process.
+     */
+    virtual void DispatchEventToAPZOnly(mozilla::WidgetInputEvent* aEvent) = 0;
+
+    /**
+     * Dispatches an event that must be handled by APZ first, when APZ is
+     * enabled. If invoked in the child process, it is forwarded to the
+     * parent process synchronously.
+     */
+    virtual nsEventStatus DispatchInputEvent(mozilla::WidgetInputEvent* aEvent) = 0;
+
+    /**
+     * Confirm an APZ-aware event target. This should be used when APZ will
+     * not need a layers update to process the event.
+     */
+    virtual void SetConfirmedTargetAPZC(uint64_t aInputBlockId,
+                                        const nsTArray<mozilla::layers::ScrollableLayerGuid>& aTargets) const = 0;
+
+    /**
+     * Returns true if APZ is in use, false otherwise.
+     */
+    virtual bool AsyncPanZoomEnabled() const = 0;
+
+    /**
+     * Enables the dropping of files to a widget.
+     */
+    virtual void EnableDragDrop(bool aEnable) = 0;
+
+    /**
+     * Enables/Disables system mouse capture.
+     * @param aCapture true enables mouse capture, false disables mouse capture
+     *
+     */
+    virtual void CaptureMouse(bool aCapture) = 0;
+
+    /**
+     * Classify the window for the window manager. Mostly for X11.
+     */
+    virtual void SetWindowClass(const nsAString& xulWinType) = 0;
+
+    /**
+     * Enables/Disables system capture of any and all events that would cause a
+     * popup to be rolled up. aListener should be set to a non-null value for
+     * any popups that are not managed by the popup manager.
+     * @param aDoCapture true enables capture, false disables capture
+     *
+     */
+    virtual void CaptureRollupEvents(nsIRollupListener* aListener,
+                                     bool aDoCapture) = 0;
+
+    /**
+     * Bring this window to the user's attention.  This is intended to be a more
+     * gentle notification than popping the window to the top or putting up an
+     * alert.  See, for example, Win32 FlashWindow or the NotificationManager on
+     * the Mac.  The notification should be suppressed if the window is already
+     * in the foreground and should be dismissed when the user brings this window
+     * to the foreground.
+     * @param aCycleCount Maximum number of times to animate the window per system
+     *                    conventions. If set to -1, cycles indefinitely until
+     *                    window is brought into the foreground.
+     */
+    NS_IMETHOD GetAttention(int32_t aCycleCount) = 0;
+
+    /**
+     * Ask whether there user input events pending.  All input events are
+     * included, including those not targeted at this nsIwidget instance.
+     */
+    virtual bool HasPendingInputEvent() = 0;
+
+    /**
+     * Set the background color of the window titlebar for this widget. On Mac,
+     * for example, this will remove the grey gradient and bottom border and
+     * instead show a single, solid color.
+     *
+     * Ignored on any platform that does not support it. Ignored by widgets that
+     * do not represent windows.
+     *
+     * @param aColor  The color to set the title bar background to. Alpha values
+     *                other than fully transparent (0) are respected if possible
+     *                on the platform. An alpha of 0 will cause the window to
+     *                draw with the default style for the platform.
+     *
+     * @param aActive Whether the color should be applied to active or inactive
+     *                windows.
+     */
+    virtual void SetWindowTitlebarColor(nscolor aColor, bool aActive) = 0;
+
+    /**
+     * If set to true, the window will draw its contents into the titlebar
+     * instead of below it.
+     *
+     * Ignored on any platform that does not support it. Ignored by widgets that
+     * do not represent windows.
+     * May result in a resize event, so should only be called from places where
+     * reflow and painting is allowed.
+     *
+     * @param aState Whether drawing into the titlebar should be activated.
+     */
+    virtual void SetDrawsInTitlebar(bool aState) = 0;
+
+    /*
+     * Determine whether the widget shows a resize widget. If it does,
+     * aResizerRect returns the resizer's rect.
+     *
+     * Returns false on any platform that does not support it.
+     *
+     * @param aResizerRect The resizer's rect in device pixels.
+     * @return Whether a resize widget is shown.
+     */
+    virtual bool ShowsResizeIndicator(LayoutDeviceIntRect* aResizerRect) = 0;
+
+    /**
+     * Return the popup that was last rolled up, or null if there isn't one.
+     */
+    virtual nsIContent* GetLastRollup() = 0;
+
+    /**
+     * Begin a window resizing drag, based on the event passed in.
+     */
+    NS_IMETHOD BeginResizeDrag(mozilla::WidgetGUIEvent* aEvent,
+                               int32_t aHorizontal,
+                               int32_t aVertical) = 0;
+
+    /**
+     * Begin a window moving drag, based on the event passed in.
+     */
+    NS_IMETHOD BeginMoveDrag(mozilla::WidgetMouseEvent* aEvent) = 0;
+
+    enum Modifiers {
+        CAPS_LOCK = 0x01, // when CapsLock is active
+        NUM_LOCK = 0x02, // when NumLock is active
+        SHIFT_L = 0x0100,
+        SHIFT_R = 0x0200,
+        CTRL_L = 0x0400,
+        CTRL_R = 0x0800,
+        ALT_L = 0x1000, // includes Option
+        ALT_R = 0x2000,
+        COMMAND_L = 0x4000,
+        COMMAND_R = 0x8000,
+        HELP = 0x10000,
+        FUNCTION = 0x100000,
+        NUMERIC_KEY_PAD = 0x01000000 // when the key is coming from the keypad
+    };
+    /**
+     * Utility method intended for testing. Dispatches native key events
+     * to this widget to simulate the press and release of a key.
+     * @param aNativeKeyboardLayout a *platform-specific* constant.
+     * On Mac, this is the resource ID for a 'uchr' or 'kchr' resource.
+     * On Windows, it is converted to a hex string and passed to
+     * LoadKeyboardLayout, see
+     * http://msdn.microsoft.com/en-us/library/ms646305(VS.85).aspx
+     * @param aNativeKeyCode a *platform-specific* keycode.
+     * On Windows, this is the virtual key code.
+     * @param aModifiers some combination of the above 'Modifiers' flags;
+     * not all flags will apply to all platforms. Mac ignores the _R
+     * modifiers. Windows ignores COMMAND, NUMERIC_KEY_PAD, HELP and
+     * FUNCTION.
+     * @param aCharacters characters that the OS would decide to generate
+     * from the event. On Windows, this is the charCode passed by
+     * WM_CHAR.
+     * @param aUnmodifiedCharacters characters that the OS would decide
+     * to generate from the event if modifier keys (other than shift)
+     * were assumed inactive. Needed on Mac, ignored on Windows.
+     * @param aObserver the observer that will get notified once the events
+     * have been dispatched.
+     * @return NS_ERROR_NOT_AVAILABLE to indicate that the keyboard
+     * layout is not supported and the event was not fired
+     */
+    virtual nsresult SynthesizeNativeKeyEvent(int32_t aNativeKeyboardLayout,
+                                              int32_t aNativeKeyCode,
+                                              uint32_t aModifierFlags,
+                                              const nsAString& aCharacters,
+                                              const nsAString& aUnmodifiedCharacters,
+                                              nsIObserver* aObserver) = 0;
+
+    /**
+     * Utility method intended for testing. Dispatches native mouse events
+     * may even move the mouse cursor. On Mac the events are guaranteed to
+     * be sent to the window containing this widget, but on Windows they'll go
+     * to whatever's topmost on the screen at that position, so for
+     * cross-platform testing ensure that your window is at the top of the
+     * z-order.
+     * @param aPoint screen location of the mouse, in device
+     * pixels, with origin at the top left
+     * @param aNativeMessage *platform-specific* event type (e.g. on Mac,
+     * NSMouseMoved; on Windows, MOUSEEVENTF_MOVE, MOUSEEVENTF_LEFTDOWN etc)
+     * @param aModifierFlags *platform-specific* modifier flags (ignored
+     * on Windows)
+     * @param aObserver the observer that will get notified once the events
+     * have been dispatched.
+     */
+    virtual nsresult SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
+                                                uint32_t aNativeMessage,
+                                                uint32_t aModifierFlags,
+                                                nsIObserver* aObserver) = 0;
+
+    /**
+     * A shortcut to SynthesizeNativeMouseEvent, abstracting away the native message.
+     * aPoint is location in device pixels to which the mouse pointer moves to.
+     * @param aObserver the observer that will get notified once the events
+     * have been dispatched.
+     */
+    virtual nsresult SynthesizeNativeMouseMove(LayoutDeviceIntPoint aPoint,
+                                               nsIObserver* aObserver) = 0;
+
+    /**
+     * Utility method intended for testing. Dispatching native mouse scroll
+     * events may move the mouse cursor.
+     *
+     * @param aPoint            Mouse cursor position in screen coordinates.
+     *                          In device pixels, the origin at the top left of
+     *                          the primary display.
+     * @param aNativeMessage    Platform native message.
+     * @param aDeltaX           The delta value for X direction.  If the native
+     *                          message doesn't indicate X direction scrolling,
+     *                          this may be ignored.
+     * @param aDeltaY           The delta value for Y direction.  If the native
+     *                          message doesn't indicate Y direction scrolling,
+     *                          this may be ignored.
+     * @param aDeltaZ           The delta value for Z direction.  If the native
+     *                          message doesn't indicate Z direction scrolling,
+     *                          this may be ignored.
+     * @param aModifierFlags    Must be values of Modifiers, or zero.
+     * @param aAdditionalFlags  See nsIDOMWidnowUtils' consts and their
+     *                          document.
+     * @param aObserver         The observer that will get notified once the
+     *                          events have been dispatched.
+     */
+    virtual nsresult SynthesizeNativeMouseScrollEvent(LayoutDeviceIntPoint aPoint,
+                                                      uint32_t aNativeMessage,
+                                                      double aDeltaX,
+                                                      double aDeltaY,
+                                                      double aDeltaZ,
+                                                      uint32_t aModifierFlags,
+                                                      uint32_t aAdditionalFlags,
+                                                      nsIObserver* aObserver) = 0;
+
+    /*
+     * TouchPointerState states for SynthesizeNativeTouchPoint. Match
+     * touch states in nsIDOMWindowUtils.idl.
+     */
+    enum TouchPointerState {
+      // The pointer is in a hover state above the digitizer
+      TOUCH_HOVER    = (1 << 0),
+      // The pointer is in contact with the digitizer
+      TOUCH_CONTACT  = (1 << 1),
+      // The pointer has been removed from the digitizer detection area
+      TOUCH_REMOVE   = (1 << 2),
+      // The pointer has been canceled. Will cancel any pending os level
+      // gestures that would triggered as a result of completion of the
+      // input sequence. This may not cancel moz platform related events
+      // that might get tirggered by input already delivered.
+      TOUCH_CANCEL   = (1 << 3),
+
+      // ALL_BITS used for validity checking during IPC serialization
+      ALL_BITS       = (1 << 4) - 1
+    };
+
+    /*
+     * Create a new or update an existing touch pointer on the digitizer.
+     * To trigger os level gestures, individual touch points should
+     * transition through a complete set of touch states which should be
+     * sent as individual messages.
+     *
+     * @param aPointerId The touch point id to create or update.
+     * @param aPointerState one or more of the touch states listed above
+     * @param aPoint coords of this event
+     * @param aPressure 0.0 -> 1.0 float val indicating pressure
+     * @param aOrientation 0 -> 359 degree value indicating the
+     * orientation of the pointer. Use 90 for normal taps.
+     * @param aObserver The observer that will get notified once the events
+     * have been dispatched.
+     */
+    virtual nsresult SynthesizeNativeTouchPoint(uint32_t aPointerId,
+                                                TouchPointerState aPointerState,
+                                                LayoutDeviceIntPoint aPoint,
+                                                double aPointerPressure,
+                                                uint32_t aPointerOrientation,
+                                                nsIObserver* aObserver) = 0;
+
+    /*
+     * Helper for simulating a simple tap event with one touch point. When
+     * aLongTap is true, simulates a native long tap with a duration equal to
+     * ui.click_hold_context_menus.delay. This pref is compatible with the
+     * apzc long tap duration. Defaults to 1.5 seconds.
+     * @param aObserver The observer that will get notified once the events
+     * have been dispatched.
+     */
+    virtual nsresult SynthesizeNativeTouchTap(LayoutDeviceIntPoint aPoint,
+                                              bool aLongTap,
+                                              nsIObserver* aObserver);
+
+    /*
+     * Cancels all active simulated touch input points and pending long taps.
+     * Native widgets should track existing points such that they can clear the
+     * digitizer state when this call is made.
+     * @param aObserver The observer that will get notified once the touch
+     * sequence has been cleared.
+     */
+    virtual nsresult ClearNativeTouchSequence(nsIObserver* aObserver);
+
+    virtual void StartAsyncScrollbarDrag(const AsyncDragMetrics& aDragMetrics) = 0;
+
+    // If this widget supports out-of-process compositing, it can override
+    // this method to provide additional information to the compositor.
+    virtual void GetCompositorWidgetInitData(mozilla::widget::CompositorWidgetInitData* aInitData)
+    {}
+
+private:
+  class LongTapInfo
+  {
+  public:
+    LongTapInfo(int32_t aPointerId, LayoutDeviceIntPoint& aPoint,
+                mozilla::TimeDuration aDuration,
+                nsIObserver* aObserver) :
+      mPointerId(aPointerId),
+      mPosition(aPoint),
+      mDuration(aDuration),
+      mObserver(aObserver),
+      mStamp(mozilla::TimeStamp::Now())
+    {
+    }
+
+    int32_t mPointerId;
+    LayoutDeviceIntPoint mPosition;
+    mozilla::TimeDuration mDuration;
+    nsCOMPtr<nsIObserver> mObserver;
+    mozilla::TimeStamp mStamp;
+  };
+
+  static void OnLongTapTimerCallback(nsITimer* aTimer, void* aClosure);
+
+  mozilla::UniquePtr<LongTapInfo> mLongTapTouchPoint;
+  nsCOMPtr<nsITimer> mLongTapTimer;
+  static int32_t sPointerIdCounter;
+
+public:
+    /**
+     * Activates a native menu item at the position specified by the index
+     * string. The index string is a string of positive integers separated
+     * by the "|" (pipe) character. The last integer in the string represents
+     * the item index in a submenu located using the integers preceding it.
+     *
+     * Example: 1|0|4
+     * In this string, the first integer represents the top-level submenu
+     * in the native menu bar. Since the integer is 1, it is the second submeu
+     * in the native menu bar. Within that, the first item (index 0) is a
+     * submenu, and we want to activate the 5th item within that submenu.
+     */
+    virtual nsresult ActivateNativeMenuItemAt(const nsAString& indexString) = 0;
+
+    /**
+     * This is used for native menu system testing.
+     *
+     * Updates a native menu at the position specified by the index string.
+     * The index string is a string of positive integers separated by the "|"
+     * (pipe) character.
+     *
+     * Example: 1|0|4
+     * In this string, the first integer represents the top-level submenu
+     * in the native menu bar. Since the integer is 1, it is the second submeu
+     * in the native menu bar. Within that, the first item (index 0) is a
+     * submenu, and we want to update submenu at index 4 within that submenu.
+     *
+     * If this is called with an empty string it forces a full reload of the
+     * menu system.
+     */
+    virtual nsresult ForceUpdateNativeMenuAt(const nsAString& indexString) = 0;
+
+    /**
+     * This is used for testing macOS service menu code.
+     *
+     * @param aResult - the current text selection. Is empty if no selection.
+     * @return nsresult - whether or not aResult was assigned the selected text.
+     */
+    NS_IMETHOD
+    GetSelectionAsPlaintext(nsAString& aResult)
+    {
+      return NS_ERROR_NOT_IMPLEMENTED;
+    }
+
+    /**
+     * Notify IME of the specified notification.
+     *
+     * @return If the notification is mouse button event and it's consumed by
+     *         IME, this returns NS_SUCCESS_EVENT_CONSUMED.
+     */
+    NS_IMETHOD NotifyIME(const IMENotification& aIMENotification) = 0;
+
+    /**
+     * Start plugin IME.  If this results in a string getting committed, the
+     * result is in aCommitted (otherwise aCommitted is empty).
+     *
+     * aKeyboardEvent     The event with which plugin IME is to be started
+     * panelX and panelY  Location in screen coordinates of the IME input panel
+     *                    (should be just under the plugin)
+     * aCommitted         The string committed during IME -- otherwise empty
+     */
+    NS_IMETHOD StartPluginIME(const mozilla::WidgetKeyboardEvent& aKeyboardEvent,
+                              int32_t aPanelX, int32_t aPanelY,
+                              nsString& aCommitted) = 0;
+
+    /**
+     * Tells the widget whether or not a plugin (inside the widget) has the
+     * keyboard focus.  Should be sent when the keyboard focus changes too or
+     * from a plugin.
+     *
+     * aFocused  Whether or not a plugin is focused
+     */
+    virtual void SetPluginFocused(bool& aFocused) = 0;
+
+    /*
+     * Tell the plugin has focus.  It is unnecessary to use IPC
+     */
+    bool PluginHasFocus()
+    {
+      return GetInputContext().mIMEState.mEnabled == IMEState::PLUGIN;
+    }
+
+    /**
+     * Set IME candidate window position by windowless plugin.
+     */
+    virtual void SetCandidateWindowForPlugin(
+      const mozilla::widget::CandidateWindowPosition& aPosition) = 0;
+
+    /**
+     * Handle default action when PluginEvent isn't handled
+     */
+    virtual void DefaultProcOfPluginEvent(
+                   const mozilla::WidgetPluginEvent& aEvent) = 0;
+
+    /*
+     * Notifies the input context changes.
+     */
+    NS_IMETHOD_(void) SetInputContext(const InputContext& aContext,
+                                      const InputContextAction& aAction) = 0;
+
+    /*
+     * Get current input context.
+     */
+    NS_IMETHOD_(InputContext) GetInputContext() = 0;
+
+    /**
+     * Get native IME context.  This is different from GetNativeData() with
+     * NS_RAW_NATIVE_IME_CONTEXT, the result is unique even if in a remote
+     * process.
+     */
+    NS_IMETHOD_(NativeIMEContext) GetNativeIMEContext();
+
+    /*
+     * Given a WidgetKeyboardEvent, this method synthesizes a corresponding
+     * native (OS-level) event for it. This method allows tests to simulate
+     * keystrokes that trigger native key bindings (which require a native
+     * event).
+     */
+    NS_IMETHOD AttachNativeKeyEvent(mozilla::WidgetKeyboardEvent& aEvent) = 0;
+
+    /*
+     * Execute native key bindings for aType.
+     */
+    typedef void (*DoCommandCallback)(mozilla::Command, void*);
+    enum NativeKeyBindingsType
+    {
+      NativeKeyBindingsForSingleLineEditor,
+      NativeKeyBindingsForMultiLineEditor,
+      NativeKeyBindingsForRichTextEditor
+    };
+    NS_IMETHOD_(bool) ExecuteNativeKeyBinding(
+                        NativeKeyBindingsType aType,
+                        const mozilla::WidgetKeyboardEvent& aEvent,
+                        DoCommandCallback aCallback,
+                        void* aCallbackData) = 0;
+
+    /*
+     * Retrieves preference for IME updates
+     */
+    virtual nsIMEUpdatePreference GetIMEUpdatePreference() = 0;
+
+    /*
+     * Call this method when a dialog is opened which has a default button.
+     * The button's rectangle should be supplied in aButtonRect.
+     */
+    NS_IMETHOD OnDefaultButtonLoaded(const LayoutDeviceIntRect& aButtonRect) = 0;
+
+    /**
+     * Return true if this process shouldn't use platform widgets, and
+     * so should use PuppetWidgets instead.  If this returns true, the
+     * result of creating and using a platform widget is undefined,
+     * and likely to end in crashes or other buggy behavior.
+     */
+    static bool
+    UsePuppetWidgets()
+    {
+      return XRE_IsContentProcess();
+    }
+
+    /**
+     * Allocate and return a "puppet widget" that doesn't directly
+     * correlate to a platform widget; platform events and data must
+     * be fed to it.  Currently used in content processes.  NULL is
+     * returned if puppet widgets aren't supported in this build
+     * config, on this platform, or for this process type.
+     *
+     * This function is called "Create" to match CreateInstance().
+     * The returned widget must still be nsIWidget::Create()d.
+     */
+    static already_AddRefed<nsIWidget>
+    CreatePuppetWidget(TabChild* aTabChild);
+
+    /**
+     * Allocate and return a "plugin proxy widget", a subclass of PuppetWidget
+     * used in wrapping a PPluginWidget connection for remote widgets. Note
+     * this call creates the base object, it does not create the widget. Use
+     * nsIWidget's Create to do this.
+     */
+    static already_AddRefed<nsIWidget>
+    CreatePluginProxyWidget(TabChild* aTabChild,
+                            mozilla::plugins::PluginWidgetChild* aActor);
+
+    /**
+     * Reparent this widget's native widget.
+     * @param aNewParent the native widget of aNewParent is the new native
+     *                   parent widget
+     */
+    virtual void ReparentNativeWidget(nsIWidget* aNewParent) = 0;
+
+    /**
+     * Return true if widget has it's own GL context
+     */
+    virtual bool HasGLContext() { return false; }
+
+    /**
+     * Returns true to indicate that this widget paints an opaque background
+     * that we want to be visible under the page, so layout should not force
+     * a default background.
+     */
+    virtual bool WidgetPaintsBackground() { return false; }
+
+    virtual bool NeedsPaint() {
+       return IsVisible() && !GetBounds().IsEmpty();
+    }
+
+    /**
+     * Get the natural bounds of this widget.  This method is only
+     * meaningful for widgets for which Gecko implements screen
+     * rotation natively.  When this is the case, GetBounds() returns
+     * the widget bounds taking rotation into account, and
+     * GetNaturalBounds() returns the bounds *not* taking rotation
+     * into account.
+     *
+     * No code outside of the composition pipeline should know or care
+     * about this.  If you're not an agent of the compositor, you
+     * probably shouldn't call this method.
+     */
+    virtual LayoutDeviceIntRect GetNaturalBounds() {
+        return GetBounds();
+    }
+
+    /**
+     * Set size constraints on the window size such that it is never less than
+     * the specified minimum size and never larger than the specified maximum
+     * size. The size constraints are sizes of the outer rectangle including
+     * the window frame and title bar. Use 0 for an unconstrained minimum size
+     * and NS_MAXSIZE for an unconstrained maximum size. Note that this method
+     * does not necessarily change the size of a window to conform to this size,
+     * thus Resize should be called afterwards.
+     *
+     * @param aConstraints: the size constraints in device pixels
+     */
+    virtual void SetSizeConstraints(const SizeConstraints& aConstraints) = 0;
+
+    /**
+     * Return the size constraints currently observed by the widget.
+     *
+     * @return the constraints in device pixels
+     */
+    virtual const SizeConstraints GetSizeConstraints() = 0;
+
+    /**
+     * If this is owned by a TabChild, return that.  Otherwise return
+     * null.
+     */
+    virtual TabChild* GetOwningTabChild() { return nullptr; }
+
+    /**
+     * If this isn't directly compositing to its window surface,
+     * return the compositor which is doing that on our behalf.
+     */
+    virtual CompositorBridgeChild* GetRemoteRenderer()
+    { return nullptr; }
+
+    /**
+     * Some platforms (only cocoa right now) round widget coordinates to the
+     * nearest even pixels (see bug 892994), this function allows us to
+     * determine how widget coordinates will be rounded.
+     */
+    virtual int32_t RoundsWidgetCoordinatesTo() { return 1; }
+
+    virtual void UpdateZoomConstraints(const uint32_t& aPresShellId,
+                                       const FrameMetrics::ViewID& aViewId,
+                                       const mozilla::Maybe<ZoomConstraints>& aConstraints) {};
+
+    /**
+     * GetTextEventDispatcher() returns TextEventDispatcher belonging to the
+     * widget.  Note that this never returns nullptr.
+     */
+    NS_IMETHOD_(TextEventDispatcher*) GetTextEventDispatcher() = 0;
+
+    /**
+     * GetNativeTextEventDispatcherListener() returns a
+     * TextEventDispatcherListener instance which is used when the widget
+     * instance handles native IME and/or keyboard events.
+     */
+    NS_IMETHOD_(TextEventDispatcherListener*)
+      GetNativeTextEventDispatcherListener() = 0;
+
+    virtual void ZoomToRect(const uint32_t& aPresShellId,
+                            const FrameMetrics::ViewID& aViewId,
+                            const CSSRect& aRect,
+                            const uint32_t& aFlags) = 0;
+
+    /**
+     * OnWindowedPluginKeyEvent() is called when native key event is
+     * received in the focused plugin process directly in PluginInstanceChild.
+     *
+     * @param aKeyEventData     The native key event data.  The actual type
+     *                          copied into NativeEventData depends on the
+     *                          caller.  Please check PluginInstanceChild.
+     * @param aCallback         Callback interface.  When this returns
+     *                          NS_SUCCESS_EVENT_HANDLED_ASYNCHRONOUSLY,
+     *                          the event handler has to call this callback.
+     *                          Otherwise, the caller should do that instead.
+     * @return                  NS_ERROR_* if this fails to handle the event.
+     *                          NS_SUCCESS_EVENT_CONSUMED if the key event is
+     *                          consumed.
+     *                          NS_OK if the key event isn't consumed.
+     *                          NS_SUCCESS_EVENT_HANDLED_ASYNCHRONOUSLY if the
+     *                          key event will be handled asynchronously.
+     */
+    virtual nsresult OnWindowedPluginKeyEvent(
+                       const mozilla::NativeEventData& aKeyEventData,
+                       nsIKeyEventInPluginCallback* aCallback);
+
+
+    /**
+     * LookUpDictionary shows the dictionary for the word around current point.
+     *
+     * @param aText            the word to look up dictiorary.
+     * @param aFontRangeArray  text decoration of aText
+     * @param aIsVertical      true if the word is vertical layout
+     * @param aPoint           top-left point of aText
+     */
+    virtual void LookUpDictionary(
+                   const nsAString& aText,
+                   const nsTArray<mozilla::FontRange>& aFontRangeArray,
+                   const bool aIsVertical,
+                   const LayoutDeviceIntPoint& aPoint)
+    { }
+
+protected:
+    /**
+     * Like GetDefaultScale, but taking into account only the system settings
+     * and ignoring Gecko preferences.
+     */
+    virtual double GetDefaultScaleInternal() { return 1.0; }
+
+    // keep the list of children.  We also keep track of our siblings.
+    // The ownership model is as follows: parent holds a strong ref to
+    // the first element of the list, and each element holds a strong
+    // ref to the next element in the list.  The prevsibling and
+    // lastchild pointers are weak, which is fine as long as they are
+    // maintained properly.
+    nsCOMPtr<nsIWidget> mFirstChild;
+    nsIWidget* MOZ_NON_OWNING_REF mLastChild;
+    nsCOMPtr<nsIWidget> mNextSibling;
+    nsIWidget* MOZ_NON_OWNING_REF mPrevSibling;
+    // When Destroy() is called, the sub class should set this true.
+    bool mOnDestroyCalled;
+    nsWindowType mWindowType;
+    int32_t mZIndex;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIWidget, NS_IWIDGET_IID)
+
+#endif // nsIWidget_h__